• Title/Summary/Keyword: Closed loop control

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On-Line Sliding Mode Controller Design from a Single Closed Loop Test (단일 폐루프 테스트를 통한 온라인 슬라이딩 모드 제어기 설계)

  • Bae Jun-hyung;Lim Dong-kyun;Suh Byung-sulh
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.42 no.6
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    • pp.1-8
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    • 2005
  • The calculation of parameters of a process model is modified to find better sliding mode controller for a process. A design method by Camacho has such problems as chattering and overshoot due to the Taylor the approximation errors for the time delay term of the first order model. In this paper, a new design technique for a sliding mode controller is proposed by introducing the modified Pade approximation considering the weight factor. With the proposed method, the process response can be directly used to estimate the system parameters without any numerical processing.

Optimum Tuning of Modified PID Controller using Properties of the Affine Set (아핀 집합의 특성을 이용한 변형된 PID 제어기의 최적 동조)

  • Kim Chang-Hyun;Lim Dong-Kyun;Suh Byung-Sulh
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.42 no.6
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    • pp.15-22
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    • 2005
  • In this paper, we propose a PID-PD controller and its tuning method to be modified form of PID controller that consist of the affine set of PID and PI-PD controller by analyzing relation between these controllers. The proposed tuning method controls the closed-loop system to locate between the step responses of system controlled by PID and PI-PD controller. The controller is designed by the optimum tuning method to minimize the proposed specific cost functions. Its effectiveness is examined by the case studies and their analysis.

Model Matching for Composite Asynchronous Sequential Machines in Cascade Connection (직렬 결합된 복합 비동기 순차 머신을 위한 모델 정합)

  • Yang, Jung-Min
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.5
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    • pp.253-261
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    • 2013
  • In this paper, we study the problem of controlling composite asynchronous sequential machines. The considered asynchronous machine consists of two input/state machines in cascade connection, where the output of the front machine is delivered to the input channel of the rear machine. The objective is to design a corrective controller realizing model matching such that the stable state behavior of the closed-loop system matches that of a reference model. Since the controller receives the state feedback of the rear machine only, there exists uncertainty about the present state of the front machine. We specify the existence condition for a corrective controller given the uncertainty. The design procedure for the proposed controller is described in a case study.

Development of Robust Intelligent Digital Controller for Smart Space (스마트 스페이스 구축을 위한 강인 지능형 디지털 제어기 개발)

  • Joo, Young-Hoon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.18 no.1
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    • pp.60-65
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    • 2008
  • In this paper, we concern the stability of smart space by using the robust digital controller. The proposed methodologies are based on the intelligent digital redesign (IDR). More precisely, we represent the nonlinear and uncertain analog system as the Takaki-Sugeno (T-S) fuzzy model. Then the IDR problem can be reduced to find the digital gains minimizing the norm distance between the closed-loop states of the analog and digital control. Its constructive conditions are expressed as the linear matrix inequalities (LMIs). At last, a numerical example, HVAC system, is demonstrated to visualize the feasibility of the proposed methodology.

Optimal Unity Power Factor Control of Permanent Magnet Synchronous Motor with q-axis Field by Inverse LQ Method

  • Takami, Hiroshi
    • Journal of Power Electronics
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    • v.1 no.2
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    • pp.117-126
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    • 2001
  • A synchronous motor(SM) with q-axis special field winding of which the q-axis field-current compensates and cancels armature reaction can be driven at unity power factor under the conditions of transient state as well as steady state. The motor operates in high efficiency in all conditions. However, in order to obtain maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ(ILQ) design method on a basis of the pole assignment is suitable for this problem:(1) The time constants of the output responses can be designed for desired specifications, (2) Relations between feedback gains and response of closed loop system are very clear and (3) Optimal solutions can be given by simple procedure of ILQ method without solving the Ricaati's equation, compared to the usual LQ design method. Accordingly, the ILQ method can make the responses of armature current and q-axis field-current correspond. In this paper, it is proved by numerical simulations and experiments that the ILQ method is very effective for optimal regulator design of this plant and realizes a high-performance motor with unity power factor and high efficiency.

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Parameter Identification and Error Analysis of Approximation method for Linear motors (리니어 모터의 매개변수 추정과 근사화의 오차 분석)

  • Nam, Jae-Wu;Oh, Joon-Tae;Kim, Gyu-Sik
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.49 no.4
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    • pp.61-68
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    • 2012
  • In this paper, a closed-loop sensorless stroke control system for a linear compressor has been designed. In order to estimate the piston position accurately, motor parameters are identified as a function of the piston position and the motor current. These parameters are stored in ROM table and used later for the accurate estimation of piston position. The identified motor parameters are approximated to the several surface functions in order to decrease memory size. They can also be divided into 2 or 4 subsections to decrease identification errors. The effect of the order of surface functions and division of subsections on identification errors and computation time is analyzed.

DFIG Wind Power System with a DDPWM Controlled Matrix Converter

  • Lee, Ji-Heon;Jeong, Jong-Kyou;Han, Byung-Moon;Choi, Nam-Sup;Cha, Han-Ju
    • Journal of Electrical Engineering and Technology
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    • v.5 no.2
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    • pp.299-306
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    • 2010
  • This paper proposes a new doubly-fed induction generator (DFIG) system using a matrix converter controlled by direct duty ratio pulse-width modulation (DDPWM) scheme. DDPWM is a recently proposed carrier based modulation strategy for matrix converters which employs a triangular carrier and voltage references in a voltage source inverter. By using DDPWM, the matrix converter can directly and effectively generate rotor voltages following the voltage references within the closed control loop. The operation of the proposed DFIG system was verified through computer simulation and experimental works with a hardware simulator of a wind power turbine, which was built using a motor-generator set with vector drive. The simulation and experimental results confirm that a matrix converter with a DDPWM modulation scheme can be effectively applied for a DFIG wind power system.

Modeling, Simulation and Fault Diagnosis of IPFC using PEMFC for High Power Applications

  • Darly, S.S.;Vanaja Ranjan, P.;Justus Rabi, B.
    • Journal of Electrical Engineering and Technology
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    • v.8 no.4
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    • pp.760-765
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    • 2013
  • An Interline Power Flow Controller (IPFC) is a converter based controller which compensates and balance the power flow among multi-lines within the same corridor of the multi-line subsystem. The Interline Power Flow Controller consists of a voltage source converter based Flexible AC Transmission System (FACTS) controller for series compensation. The reactive voltage injected by individual Voltage Source Converter (VSC) can be controlled to regulate active power flow in the respective line in which one VSC regulates the DC voltage, the other one controls the reactive power flows in the lines by injecting series active voltage. In this paper, a circuit model for IPFC is developed and simulation of interline power flow controller is done using the proposed circuit model. Simulation is done using MATLAB Simulink and PSPICE. The results obtained by MATLAB are compared with the results obtained by PSPICE and compared with theoretical values.

Fast Fourier Transform Analysis of Welding Penetration Depth Using 2 kW CW Nd:YAG Laser Welding Machine

  • Kim, Do-Hyung;Chung, Chin-Man;Baik, Sung-Hoon;Kim, Koung-Suk;Kim, Jin-Tae
    • Journal of the Korean Society for Nondestructive Testing
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    • v.28 no.4
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    • pp.372-376
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    • 2008
  • We report experimental results on the correlations between welding penetration depth and the frequencies of the radiation from the welding pool. Various welding samples such as SUS304, brass, SUS316, etc. have been investigated with 2 kW CW Nd:YAG laser welding machine. The radiation signals from the plume generated by the interactions between the welding sample and laser with respect to the defocusing length was measured with fiber system collecting the plume signal. Analysis of the frequencies by using fast Fourier transform (FFT) shows that the penetration depth is deep as plume signal frequencies are low, shallow penetration depth for high frequencies. Frequencies up to 250 Hz for obtained signals can be analyzed with the discrete FFT. This is the useful method fur closed loop control of the laser power with respect to the welding penetration depth and is used for real time inspection of the welding quality.

A class of actuated deployable and reconfigurable multilink structures

  • Phocas, Marios C.;Georgiou, Niki;Christoforou, Eftychios G.
    • Advances in Computational Design
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    • v.7 no.3
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    • pp.189-210
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    • 2022
  • Deployable structures have the ability to shift from a compact state to an expanded functional configuration. By extension, reconfigurability is another function that relies on embedded computation and actuators. Linkage-based mechanisms constitute promising systems in the development of deployable and reconfigurable structures with high flexibility and controllability. The present paper investigates the deployment and reconfigurability of modular linkage structures with a pin and a sliding support, the latter connected to a linear motion actuator. An appropriate control sequence consists of stepwise reconfigurations that involve the selective releasing of one intermediate joint in each closed-loop linkage, effectively reducing it to a 1-DOF "effective crank-slider" mechanism. This approach enables low self-weight and reduced energy consumption. A kinematics and finite-element analysis of different linkage systems, in all intermediate reconfiguration steps of a sequence, have been conducted for different lengths and geometrical characteristics of the members, as well as different actuation methods, i.e., direct and cable-driven actuation. The study provides insight into the impact of various structural typological and geometrical factors on the systems' behavior.